Directions

Preheat oven to 350F (175C) and line a 9x9 metal baking pan with parchment paper or grease and flour the sides and bottom of the pan.*Combine butter and sugars in a large bowl and stir until well-combined.Add eggs and vanilla extract and stir well.In a separate bowl, whisk together flour, cornstarch, baking powder, salt, and cinnamon (if using).Gradually add dry ingredients to wet until completely combined.Add oats and chocolate chips and stir until well combined.Spread cookie dough evenly into prepared baking pan and bake on 350F (175C) for 35-40 minutes or until a toothpick inserted in the center comes out clean or with a few moist crumbs.